1. Field of the Invention
The present invention relates to the housing and protection of integrated circuit chips. More specifically, the present invention relates to a package that provides electromagnetic field (EMF) shielding and thermal protection for integrated circuit chips.
2. Description of the Related Art
Modern integrated circuits require protection from self-heating effects, electromagnetic fields, electrostatic discharge, and mechanical shock in order to operate properly. In addition, the integrated circuit (IC) itself could be a source of EMF emissions that could be potentially harmful to other electronic devices in close proximity to the IC, or that could result in a violation of FCC regulations regarding EMF emissions.
These considerations have created a need for a package that will provide an IC with substantial shielding from EMF emissions originating outside of the IC package and also protect other sensitive electronic devices and the environment in general from EMF emissions originating from the IC itself. In addition, the package should provide adequate heat dissipation in order to keep the IC temperature within allowable operating limits.
Many prior art IC packages have been made that address the heat dissipation issue. These packages usually employ a post made of heat conducting material or an enclosure that incorporates a heat sink with cooling vanes to facilitate heat dissipation. Some of these packages, such as that disclosed in U.S. Pat. No. 5,175,613, entitled "PACKAGE FOR EMI, ESD, THERMAL, AND MECHANICAL SHOCK PROTECTION OF CIRCUIT CHIPS", issued Dec. 29, 1992 to C. Barker, et. al., have addressed both EMF shielding and heat dissipation. However, the physical dimensions of this package do not conform to an industry recognized package outline, such as those recognized by the Joint Electron Device Engineering Council (JEDEC) or the Electronics Industry Association of Japan (EIJA). The Barker package cannot be handled by the auto-insertion equipment that is typically used by board assemblers because of the physical dimensions and size of these packages.
Another limitation of the Barker package is that it is not possible to house both EMF-generating components and EMF-sensitive components simultaneously in the same package. The reason for this is that this package does not provide an option for shielding two or more components from each other if they are mounted in the same package. If an EMF-generating component is mounted inside this package, then the only EMF-sensitive components that are protected from EMF emissions are those that are mounted outside the package. Conversely, if an EMF-sensitive component is mounted inside the package, then it will only be protected from EMF emissions emanating from electronic devices disposed outside the package.
Other packages, such as those disclosed in U.S. Pat. No. 5,184,211, entitled "APPARATUS FOR PACKAGING AND COOLING INTEGRATED CIRCUIT CHIPS", issued Feb. 2, 1993 to L. Fox, U.S. Pat. No. 3,902,148, entitled "SEMICONDUCTOR LEAD STRUCTURE AND ASSEMBLY AND METHOD FOR FABRICATING SAME", issued Aug. 26, 1975 to J. Drees, et. al., and U.S. Pat. No. 5,172,213, entitled "MOLDED CIRCUIT PACKAGE HAVING HEAT DISSIPATING POST" issued Dec. 15, 1992 to M. Zimmerman address only the heat dissipation issue. The Fox package, like the Barker package, does not conform to an industry recognized package outline.